Process and agent for anchoring securing elements in drill holes

ABSTRACT

The process for anchoring securing elements in drill holes, particularly screws, nails, anchors, clamp irons, and bolts, by using two-component adhesives and metal additives, is such that 
     a) the drill holes optionally rebored, cleaned and degreased in advance are filled up to from half to three quarters with a compressible mixture of highly wear-resistant fibers or chips made of metals, polymers and/or ceramics with an average length smaller than half the drill hole diameter, subsequently, a blocker is optionally added, then both adhesive components are introduced successively or simultaneously, and then the residual portion of the required amount of fibers or chips is filled in, or 
     b) a kneadable mixture is prepared from a compressible mixture of highly wear-resistant fibers or chips with an average length smaller than half the drill hole diameter and both adhesive components, and the mass is forced into the drill holes, 
     and subsequently, the securing elements are inserted and optionally secured. A low molecular weight fungicide may be added to the two-component adhesive to renovate the part of the support adjacent to the drill hole, which support is made of wood, brickwork or concrete.

BACKGROUND OF THE INVENTION

This invention is predominantly directed to a process for anchoringsecuring elements in drill holes, particularly screws, nails, anchors,clamp irons, and bolts, by using two-component adhesives and metalenforcement. The invention is particularly useful in older,renovation-requiring drill holes in sleepers of track systems as well asin drill holes in floors, walls or ceilings made of wood, concrete,steel or brickwork. In the following specification and claims, sleepers,floors, walls, and ceilings will be referred to as supports.

One process for securing screws or nails, particularly sleeper screws orsleeper nails in material which can deteriorate is known from GermanPatent 1,948,339 and the Additional Application 2,413,479. Herein,specifically formed clamp pieces or tube-shaped wire meshes or wiregrids are used as metal reinforcement. This process has proven useful inpractice, but only in cases where the dimensions of the drill hole andthe metal reinforcement are well-balanced with respect to each other.For optimum securing, drill holes having different drill hole diametersrequire differently dimensioned metal reinforcement. As such work mostfrequently is carried out by unskilled or semi-skilled personnel, thereis the danger of improper metal reinforcement choice and thus,unsatisfactory results. Another drawback of the known process is thatthe screws once tightened using the desired torque are intended not tobe loosened again. However, subsequent to the initial tightening, it isoften desired to re-loosen the screw and to make corrections on thesystem to be secured.

Another drawback of the known process is that the two-componentadhesives must be premixed before they can be filled into the drillhole. Thus, relatively small amounts must be prepared freshly again andagain since setting of the completely mixed two-component adhesive willbegin within a few minutes.

SUMMARY OF THE INVENTION

It is the object of the invention to improve and simplify the knownprocess, avoiding the above-mentioned drawbacks. Moreover, the processof the invention is intended to be suitable for drill holes in ceilings(overhead operation) and walls.

Surprisingly, this object is achieved in that

a) the drill holes optionally rebored, cleaned and degreased in advanceare filled up to from half to three quarters with a compressible mixtureof highly wear-resistant fibers or chips made of metals, polymers and/orceramics with an average length smaller than half the drill holediameter, subsequently, from 1 to 2 drops of a blocker are optionallyadded, then both adhesive components are introduced successively orsimultaneously, and then the residual portion of the required amount offibers or chips is filled in, or

b) a kneadable mixture is prepared from a compressible mixture of highlywear-resistant fibers or chips with an average length smaller than halfthe drill hole diameter and both adhesive components, and the mass isforced into the drill holes which, in extreme cases, are rebored,cleaned and degreased in advance.

and when using securing elements without a self-cutting thread, a centerhole is preformed and subsequently, the securing elements are insertedand optionally secured.

While mode a) of the process according to the invention is suitable fordrill holes in track systems, particularly in sleepers requiringrenovation, or drill holes in floors, mode b) is applied for drill holesin wall and ceiling constructions. For both modes of the process, thesupport is not significant: it may consist of wood, concrete, steel orbrickwork.

The process of the invention does not require pre-mixing the twocomponents of the adhesive. Rather, they may be introduced into thedrill hole successively or simultaneously, also in unmixed condition, ormay be mixed with said fibers or chips to give the kneadable mass. Theadditive in the form of fibers or chips which is used according to theinvention provides good and sufficient mixing of the components in thedrill hole.

Furthermore, the process according to the invention permits the use ofscrews as the securing elements and allows tightening them using theintended torque. Hereby, an immediate nonpositive joint between screwand drill hole wall results. It is even possible to loosen the screwrepeatedly during the pot life of the components and to re-tighten itsecurely without endangering the good overall result. Tightening torquesof up to 500 Nm can be achieved without any problem, with the looseningtorque being about 200 Nm.

Stripping experiments on screws mounted into 30-year-old clamps usingthe process of the invention have shown that with a tightening torque ofabout 50 Nm, a stripping force of up to 67 kN is necessary.

Subsequent to the pot life of the liquid components, i.e., during thesetting phase, the screw joint should not be loosened or tightenedanymore, if possible. Generally, this setting phase will take from twoto five hours. The curing period depends on mixture balance, ambient andmaterial temperature. Subsequent to the setting phase, it is possibleagain to repeatedly unscrew the screw and screw it in again. Forexample, this may be necessary to exchange a broken spring washer. Incase threads have been damaged by bent screws, a new screw may becemented into the drill hole.

In order to facilitate removal of the screw after curing, it isadvantageous to wipe the screw with an oily rag prior to anchoring inthe drill hole, i.e., the oil serves as a release agent between screwand the cured mixture of metal chips and two-component adhesive.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A liquid component A having a formulation of aliphatic andcycloaliphatic epoxy resins, mono- and bifunctional reactive thinnersand primers, and a liquid component B having a formulation of aliphaticand/or cycloaliphatic polyamines, polyamidoamines, Mannich bases, andprimers, and optionally, promoters have proven useful in the invention.

Good results are also obtained when using as the components C and D ofthe adhesive, a liquid component C having a formulation of diisocyanateswith primers and common additives, and as the liquid component D, aformulation of multifunctional alcohols with primers and adjuvants.

For extreme cases, i.e., for renovating through-holes, in track systems,for example, from 1 to 2 drops of a blocker are added which, on mixingwith metal chips, causes thickening of the adhesive system comprisingthe two components of the adhesive. Such thickening or solidifying ofthe material prevents falling through the screw hole which is open atthe bottom. Suitable as blockers for the process according to theinvention are low-viscosity diisocyanates and methacrylates.

In order to renovate the part of the support adjacent to the unstablehole, which support is made of wood, brickwork or concrete, a lowmolecular weight fungicide may be added to the two components of theadhesive A and B or C and D, which gradually migrates outwardpenetrating into the rotten part of the support (e.g., a wooden sleeper)and thus, on a medium-term, prevents further infestation by fungi or atleast, slows it down.

The fungicides must be compatible with the corresponding components,without reacting with same. In addition, their molecular size must besmall, i.e., the molecular weight must be relatively low. This isrequired in order not to inhibit diffusion of the fungicides from theadhesives matrix into the adjacent wood or brickwork.

The ideal molecular size or the ideal molecular weight depends on theaverage size or the average molecular weight of the adhesive componentsand the "mesh width" of the spatial network constituted in bonding.Narrow "meshes" require smaller molecules, larger "meshes" allow forlarger molecules. Large "meshes" in the spatial lattice of the adhesivematrix permit more rapid diffusion than small meshes do.

According to the invention, to said two components of the adhesive areadded as the low molecular weight fungicide, for instance. Rowalin GZ(Biochema Schwaben, Dr. Lehmann & Co., Memmingen), Rodurol F2 (BiochemaSchwahen, Dr. Lehmann & Co., Memmingen) or Konservan RT (ThorChemieGmbH. Speyer) in an amount of from 0.25 to 10% by weight, based on saidtwo components or the adhesive. Preferably, Rowalin GZ is used in anamount of from 0.25 to 3.5% by weight (based on said two components ofthe adhesive).

For example, the course of operation for a screw hole renovation intrack systems is as follows:

1. The old screw is removed from the damaged hole in the sleeper. Priorto reuse, rough dirt, oil and grease residues are removed from the screwusing a rag.

2. The screw hole is cleaned from loose dirt and solid particles and, inthe case of wood, from rotten wood. Optionally, this may be done byfurther reboring.

3. About half the compressible mixture of highly wear-resistant metalchips with an average length smaller than half the drill hole diameteris filled in.

With a hole diameter of 26 mm, chips of highly wear-resistant metals oralloys are suitable with a length of from 0.1 to 15 mm as long as theaverage length is smaller than half the drill hole diameter. Preferably,chips having lengths of from 0.1 to 7 mm are employed. Morespecifically, if the length of chips is varying and has a relativelybroad grading line, the mixture is well-compressible.

4. Liquid component A is filled in (with urethane adhesives, liquidcomponent C).

5. Liquid component B is filled in (with urethane adhesives, liquidcomponent D).

Indeed, it is possible to premix components A and B (with urethaneadhesives, components C and D) and to add them as a mixture.

6 The required residual amount of chips is charged to about 1 cm belowthe edge of the drill hole.

7. When using screws lacking a self-cutting thread, a center hole mustbe preformed by means of a mandrel or the like.

8. The screw is inserted and tightened using the designated torque.

Using this procedure which is simple even for unskilled personnel, arate of about 180 renovated drill holes per hour is achieved.

As described above, the process according to the invention is suitablenot only for anchoring screws in renovation-requiring drill holes oftrack systems but generally, for anchoring securing elements, morespecifically, nails, anchors, clamp irons, and bolts, in drill holes,for example, in concrete floors but, above all, also in wall and ceilingconstructions (mode b). The kneadable mass prepared according to mode b)is forced into the preformed holes of the wall or ceiling construction,the securing element is forced or screwed into this solids kneading plugand tightened. As a rule, the stew has a diameter smaller than the holeby 2 min. Likewise, however, screws too small in size having evensmaller diameter, or other securing elements may be attachednonpositively with the process of the invention. Since the kneadablemass cures only after 2 to 5 hrs, a larger amount of plugging mass, onceprepared, can be used to plug a large number of drill holes. Thus, thesize of the drill holes plays a minor role since the mass is suitablefor both large and small drill holes.

The process according to the invention is particularly suitable in caseswhere the anchoring must meet high requirements and where it isnonetheless necessary in both mounting and at a later time to loosen thescrew once again and to re-tighten it.

At the same time, the process of the invention using addition offungicide has the advantage of likewise renovating that part of thesupport adjacent to the drill hole, which support is made of wood,brickwork or concrete.

In cases where polymers or ceramics are used as the fibers or chipsinstead of metals, the final anchoring also represents good electricalinsulation. This may be advantageous for anchoring securing elements inoverhead line construction.

Thus, at first, the present invention is directed to the process foranchoring securing elements in drill holes, particularly screws, nails,anchors, clamp irons, and bolts, as described above. Further, theinvention is directed to an agent for anchoring securing elements indrill holes, consisting of a compressible mixture of highlywear-resistant fibers or chips with an average length smaller than halfthe drill hole diameter and two components of an adhesive andoptionally, a blocker. According to another aspect, an agent is usedcontaining a low molecular weight fungicide to likewise renovate, ifnecessary, the rotten drill hole environment infested by fungi.Preferably, the agent employed has a quantity ratio between fibers orchips (solids proportion) and the two components of the adhesive andoptionally blocker and fungicide (liquid proportion) of 90% by mass to10% by mass.

Finally, the invention is directed to the use of compressible mixturesof highly wear-resistant fibers or chips with an average length smallerthan half the drill hole diameter as an additive in two-componentadhesives for anchoring securing elements such as screws in drill holes.

Preferred embodiments of the process according to the invention will bediscussed in detail in the following examples.

EXAMPLE 1

Sleepers requiring renovation were rebored to a depth of about 180 mmand a width of 26 mm. Into the drill holes, metal chips were filledhaving lengths of from 3 to 7 mm. Only about 3±2% had a length of <3 mm.Less than 5% had a length of more than 7 mm. Next, from 10 to 15 g offreshly prepared two-component adhesive was used. The two-componentadhesive consisted of liquid component A consisting of a formulation ofaliphatic and cycloaliphatic epoxy resins, mono- and bifunctionalreactive thinners and primers to control theology, and a liquidcomponent B consisting of a formulation of aliphatic and cycloaliphaticpolyamines, polyamidoamines, primers, and promoters. On top of thislayer of two-component adhesive, a layer of metal chips was introducedhaving diameters of between 0.1 to 7 mm. About half of these chips had alength of <1 mm. Only about 15 to 25% had a length of from 4 to 7 mm. Toaccomodate screws lacking a self-cutting thread, a center hole waspreformed.

Into the such prepared drill holes, common screws for rail securing werescrewed in. Even after 10 min it was possible to loosen them or tightenthem faster. After 6 hrs the two-component adhesive had cured to suchstrength that the screws could be unscrewed and screwed in again withoutdestroying the freshly formed thread of cemented metal chips.

EXAMPLE 2

For plugging holes preformed in construction or holes to be drilledfreshly in floors, walls or overhead, a kneadable mass is prepared fromthe adhesive components A and B or C and D and the highly wear-resistantmetal chips. The metal chips, the average length of which should besmaller than half the hole diameter, are kneaded with the premixedadhesive components A and B or C and D. The adhesive proportion Crelative to the metal chips depends on grading line and shape of latterand is between 5% by mass and 15% by mass. The such obtained "solidskneading plug" is forced into the present hole and is compressed byforce. Screws having a self-cutting thread may then be screwed indirectly. With screws lacking a self-cutting thread, a center holeanalogous to Example 1 must be preformed. The amount of solids kneadingplug to be used depends on hole size and screws to be used.

It was found that in such way screws having significantly smallerdiameter than is the hole diameter also afford nonpositive joints.

EXAMPLE 3

In tunnel and bridge construction, recesses and holes are planned tocover the demand for plug holes arising later, without subsequentlydamaging the concrete body by drilling. However, since at the time ofplanning the precise purpose of use of the securing element to beemployed is not yet known definitely, the largest required diameter ofthe holes required later is chosen as a precaution, for example, 16 mmfor powerful heavy trucks. These holes are charged according to Example1 or 2. Thicker screws are screwed in before curing, thinner screws mayalso be screwed in after curing and have good nonpositive joints.

We claim:
 1. A process for anchoring a securing element in a drill hole,comprising:a) filling the drill hole to from half to three quarters witha compressible mixture of highly wear-resistant fibers or chips made ofmetals, polymers and or ceramics with an average length smaller thanhalf the drill hole diameter, introducing both adhesive components of atwo-component adhesive, then filling in the residual portion of therequired amount of fibers or chips; c) then inserting the securingelement into the drill hole.
 2. The process according to claim 1,wherein the two-component adhesive comprises a liquid component A havinga formulation of aliphatic and cycloaliphatic epoxy resins, mono- andbifunctional reactive thinners and primers, and a liquid component Bhaving a formulation of aliphatic and/or cycloaliphatic polyamines,polyamidoamines, Mannich bases, and primers.
 3. The process according toclaim 2, wherein said adhesive further comprises a promoter.
 4. Theprocess according to claim 1, wherein the two-component adhesivecomprises a liquid component C having a formulation of diisocyanateswith primers and common additives, a liquid component D having aformulation of multifunctional alcohols with primers and adjuvants. 5.The process according to claim 1, further comprising adding a lowmolecular weight fungicide to the two components of the adhesive.
 6. Theprocess according to claim 5, wherein the low molecular weightfungicide, is Rowalin GZ, Rodurol F2 or Konservan RT in an amount offrom 0.25 to 10% by weight relative to both components of the adhesive.7. The process according to claim 6, wherein said fungicide is RowalinGZ and is used in an amount of from 0.25 to 3.5% by weight.
 8. Theprocess according to claim 1, further comprising adding a blockingamount of a low-viscosity diisocyanate or methacrylate.
 9. The processaccording to claim 8, wherein said blocking amount is 1-2 drops.
 10. Theprocess according to claim 1, wherein said securing elements areselected from the group consisting of screws, nails, anchors, clampirons, and bolts.
 11. The process according to claim 1, furthercomprising reboring, cleaning, and degreasing the holes before fillingthe same with said compressible mixture in procedure a).
 12. The processaccording to claim 1, further comprising adding a blocker after fillingthe holes with the compressible mixture but before introducing theadhesive components.
 13. The process according to claim 1, wherein saidadhesive components are introduced successively.
 14. The processaccording to claim 1, wherein said adhesive components are introducedsimultaneously.
 15. The process according to claim 5, further comprisingpreforming a center hole before inserting said securing element whenusing securing elements without self-cutting threads.